Research IndicatorsGraph generated 10 March 2017 using data from PubMed using criteria.
Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic. Tag cloud generated 10 March, 2017 using data from PubMed, MeSH and CancerIndex
Specific Cancers (4)
Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.
Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).
OMIM, Johns Hopkin University
Referenced article focusing on the relationship between phenotype and genotype.
International Cancer Genome Consortium.
Summary of gene and mutations by cancer type from ICGC
Cancer Genome Anatomy Project, NCI
COSMIC, Sanger Institute
Somatic mutation information and related details
GEO Profiles, NCBI
Search the gene expression profiles from curated DataSets in the Gene Expression Omnibus (GEO) repository.
Latest Publications: CHFR (cancer-related)
Eyvani H, Moghaddaskho F, Kabuli M, et al.Arsenic trioxide induces cell cycle arrest and alters DNA methylation patterns of cell cycle regulatory genes in colorectal cancer cells.
Life Sci. 2016; 167:67-77 [PubMed
] Related Publications
AIMS: Cell cycle dysregulation is important in tumorigenesis. Transcriptional silencing of cell cycle regulatory genes, due to DNA methylation, is a common epigenetic event in malignancies. As2O3 has been shown to induce cell cycle arrest and also to be a potential hypomethylating agent. Our study aimed to investigate DNA methylation patterns of cell cycle regulatory genes promoters, the effects of Arsenic trioxide (As2O3) on the methylated genes and cell cycle distribution in colorectal cancer (CRC) cell lines.
MAIN METHODS: The methylation-specific PCR (MSP) and/or restriction enzyme-based methods were used to study the promoter methylation patterns of 24 cell cycle regulatory genes in CRC cell lines. Gene expression level and cell cycle distribution were determined by Real-time PCR and flow cytometric analyses, respectively.
KEY FINDINGS: Our methylation analysis indicated that only promoters of RBL1 (p107), CHFR and p16 genes were aberrantly methylated in three cell lines. As2O3 significantly decreased DNA methylation in promoter regions of these genes and restored their expression. We found that As2O3 significantly reduced the expression of DNA methyltransferase 1 (DNMT1) and increased arsenic methyltransferase (AS3MT). Furthermore, As2O3 altered transcriptional activity of several unmethylated cell cycle regulatory genes including cyclin B1, E1, D1, GADD45A and p21. Cell cycle flow cytometry analysis showed As2O3 induced G2/M arrest in all three cell lines.
SIGNIFICANCE: These data suggest that demethylation and alteration in the expression level of the cell cycle-related genes may be possible mechanisms in As2O3-induced cell cycle arrest in colorectal cancer cells.
Esophageal cancer is one of the most common malignancies in the world. Squamous cell carcinoma accounts for approximately 90 % of esophageal cancer cases. Genetic and epigenetic changes have been found to accumulate during the development of various cancers, including esophageal squamous carcinoma (ESCC). Tobacco smoking and alcohol consumption are two major risk factors for ESCC, and both tobacco and alcohol were found to induce methylation changes in ESCC. Growing evidence demonstrates that aberrant epigenetic changes play important roles in the multiple-step processes of carcinogenesis and tumor progression. DNA methylation may occur in the key components of cancer-related signaling pathways. Aberrant DNA methylation affects genes involved in cell cycle, DNA damage repair, Wnt, TGF-β, and NF-κB signaling pathways, including P16, MGMT, SFRP2, DACH1, and ZNF382. Certain genes methylated in precursor lesions of the esophagus demonstrate that DNA methylation may serve as esophageal cancer early detection marker, such as methylation of HIN1, TFPI-2, DACH1, and SOX17. CHFR methylation is a late stage event in ESCC and is a sensitive marker for taxanes in human ESCC. FHIT methylation is associated with poor prognosis in ESCC. Aberrant DNA methylation changes may serve as diagnostic, prognostic, and chemo-sensitive markers. Characterization of the DNA methylome in ESCC will help to better understand its mechanisms and develop improved therapies.
Sepulveda JL, Gutierrez-Pajares JL, Luna A, et al.High-definition CpG methylation of novel genes in gastric carcinogenesis identified by next-generation sequencing.
Mod Pathol. 2016; 29(2):182-93 [PubMed
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Gastric cancers are the most frequent gastric malignancy and usually arise in the sequence of Helicobacter pylori-associated chronic gastritis. CpG methylation is a central mechanism of epigenetic gene regulation affecting cancer-related genes, and occurs early in gastric carcinogenesis. DNA samples from non-metaplastic gastric mucosa with variable levels of gastritis (non-metaplastic mucosa), intestinal metaplasia, or gastric cancer were screened with methylation arrays for CpG methylation of cancer-related genes and 30 gene targets were further characterized by high-definition bisulfite next-generation sequencing. In addition, data from The Cancer Genome Atlas were analyzed for correlation of methylation with gene expression. Overall, 13 genes had significantly increased CpG methylation in gastric cancer vs non-metaplastic mucosa (BRINP1, CDH11, CHFR, EPHA5, EPHA7, FGF2, FLI1, GALR1, HS3ST2, PDGFRA, SEZ6L, SGCE, and SNRPN). Further, most of these genes had corresponding reduced expression levels in gastric cancer compared with intestinal metaplasia, including novel hypermethylated genes in gastric cancer (FLI1, GALR1, SGCE, and SNRPN), suggesting that they may regulate neoplastic transformation from non-malignant intestinal metaplasia to cancer. Our data suggest a tumor-suppressor role for FLI1 in gastric cancer, consistent with recently reported data in breast cancer. For the genes with strongest methylation/expression correlation, namely FLI1, the expression was lowest in microsatellite-unstable tumors compared with other gastric cancer molecular subtypes. Importantly, reduced expression of hypermethylated BRINP1 and SGCE was significantly associated with favorable survival in gastric cancer. In summary, we report novel methylation gene targets that may have functional roles in discrete stages of gastric carcinogenesis and may serve as biomarkers for diagnosis and prognosis of gastric cancer.
Luzón-Toro B, Bleda M, Navarro E, et al.Identification of epistatic interactions through genome-wide association studies in sporadic medullary and juvenile papillary thyroid carcinomas.
BMC Med Genomics. 2015; 8:83 [PubMed
] Free Access to Full Article Related Publications
BACKGROUND: The molecular mechanisms leading to sporadic medullary thyroid carcinoma (sMTC) and juvenile papillary thyroid carcinoma (PTC), two rare tumours of the thyroid gland, remain poorly understood. Genetic studies on thyroid carcinomas have been conducted, although just a few loci have been systematically associated. Given the difficulties to obtain single-loci associations, this work expands its scope to the study of epistatic interactions that could help to understand the genetic architecture of complex diseases and explain new heritable components of genetic risk.
METHODS: We carried out the first screening for epistasis by Multifactor-Dimensionality Reduction (MDR) in genome-wide association study (GWAS) on sMTC and juvenile PTC, to identify the potential simultaneous involvement of pairs of variants in the disease.
RESULTS: We have identified two significant epistatic gene interactions in sMTC (CHFR-AC016582.2 and C8orf37-RNU1-55P) and three in juvenile PTC (RP11-648k4.2-DIO1, RP11-648k4.2-DMGDH and RP11-648k4.2-LOXL1). Interestingly, each interacting gene pair included a non-coding RNA, providing thus support to the relevance that these elements are increasingly gaining to explain carcinoma development and progression.
CONCLUSIONS: Overall, this study contributes to the understanding of the genetic basis of thyroid carcinoma susceptibility in two different case scenarios such as sMTC and juvenile PTC.
Gao L, Liu F, Zhang H, et al.CHFR hypermethylation, a frequent event in acute myeloid leukemia, is independently associated with an adverse outcome.
Genes Chromosomes Cancer. 2016; 55(2):158-68 [PubMed
] Related Publications
The CpG island of the promoter region of the checkpoint with fork-head associated and ring finger gene (CHFR), a mitotic checkpoint gene with tumor-suppressor functions, is hypermethylated in various human cancers. The objective of this study was to evaluate the frequency of aberrant CHFR promoter methylation in acute myeloid leukemia (AML) patients in an attempt to improve prognostication. CHFR promoter methylation levels were analyzed in 358 newly diagnosed AML cases and 30 healthy donors by the use of quantitative methylation-specific polymerase chain reaction. In addition, we analyzed possible association between CHFR hypermethylation and hematological characteristics, chromosome abnormalities, genetic mutations, and survival. Hypermethylation of the CHFR promoter was observed in 24% (85 of 358) AML patients, but not in healthy individuals. CHFR hypermethylation correlated significantly with SRSF2 and DNMT3A mutations. Patients with hypermethylation exhibited lower overall survival and shorter relapse-free survival than nonmethylated cases. In multivariate analysis, CHFR hypermethylation was an independent factor predicting poor overall survival but not relapse-free survival. In conclusion, hypermethylation of the CHFR promoter, frequent in AML, is associated with adverse outcome, and can thus be used for risk stratification.
Guo M, Alumkal J, Drachova T, et al.CHFR methylation strongly correlates with methylation of DNA damage repair and apoptotic pathway genes in non-small cell lung cancer.
Discov Med. 2015; 19(104):151-8 [PubMed
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DNA methylation occurs commonly in non-small cell lung cancer (NSCLC). We sought to determine the frequency and relationship of methylation of key genes involved in the pathways of mitotic checkpoint control, DNA damage repair, apoptosis, and growth factor signaling in these patients. We analyzed the DNA methylation status of eight genes (CHFR, FANCF, MGMT, p16, DAPK, ASC or TMS-1, RAR-B, and CRBP1) using nested methylation-specific PCR (MSP) on over 314 paraffin-embedded, human non-small cell lung cancer samples. We determined the methylation frequency of each gene in addition to the association of the methylation of each gene with other members of the panel. Methylation was a common event in these samples. Our methylation analysis showed frequencies of methylation of 10% for CHFR, 14% for FANCF, 30% for MGMT, 29% for p16, 17% for DAPK, 33% for ASC, 38% for RAR-B, and 7% for CRBP1. There was a strong correlation between methylation of the mitotic G2-M checkpoint gene, CHFR, and methylation of other genes in our panel involved in DNA damage repair (FANCF and MGMT) and apoptosis (DAPK and ASC) but not with other genes in our panel, including p16 (the G1-S checkpoint gene), CRBP1, or RAR-B. In addition, MGMT methylation strongly correlated with the pro-apoptotic gene, ASC. There are distinct associations of methylated genes in non-small cell lung cancer involving DNA damage repair, apoptosis, and the G2-M mitotic checkpoint control. Further studies are warranted to determine whether these methylation patterns have implications for prognosis in addition to prediction of response to chemotherapeutic agents commonly used in the treatment of non-small cell lung cancer, such as radiotherapy and platinum- or taxane-based chemotherapy.
Song A, Ye J, Zhang K, et al.Aberrant expression of the CHFR prophase checkpoint gene in human B-cell non-Hodgkin lymphoma.
Leuk Res. 2015; 39(5):536-43 [PubMed
] Related Publications
Checkpoint with FHA and Ring Finger (CHFR) is a checkpoint protein that reportedly initiates a cell cycle delay in response to microtubule stress during prophase in mitosis, which has become an interesting target for understanding cancer pathogenesis. Recently, aberrant methylation of the CHFR gene associated with gene silencing has been reported in several cancers. In the present study, we examined the expression of CHFR in B-cell non-Hodgkin lymphoma (B-NHL) in vitro and in vivo. Our results showed that the expression level of CHFR mRNA and protein was reduced in B-NHL tissue samples and B cell lines. Furthermore, CHFR methylation was detected in 39 of 122 B-NHL patients, which was not found in noncancerous reactive hyperplasia of lymph node (RH) tissues. CHFR methylation correlated with the reduced expression of CHFR, high International Prognostic Index (IPI) scores and later pathologic Ann Arbor stages of B-NHL. Treatment with demethylation reagent, 5-Aza-dC, could eliminate the hypermethylation of CHFR, enhance CHFR expression and cell apoptosis and inhibit the cell proliferation of Raji cells, which could be induced by high expression of CHFR in Raji cells. Our results indicated that aberrant methylation of CHFR may be associated with the pathogenesis, progression for B-NHL, which might be a novel molecular marker as prognosis and treatment for B-NHL.
BACKGROUND: CHFR expression has previously been established as a powerful predictor for response to taxane based first-line chemotherapy in non-small cell lung cancer. It is currently unknown however, if reduced CHFR expression correlates with certain molecular subtypes of lung cancer.
PURPOSE: In order to determine which patients may benefit from CHFR biomarker testing we conducted the present study to characterize clinical and molecular characteristics of patients with reduced vs. high CHFR expression.
APPROACH: We utilized the extensive molecular and clinical data of the most recent adeno- and squamous cell carcinoma datasets from The Cancer Genome Atlas (TCGA) project. CHFR expression, analyzed by RNA-seq, was classified as high vs. low based on the median CHFR expression level and correlated with the presence or absence of lung cancer specific mutations (EGFR, KRAS, ALK, MET, ERBB2, TP53, STK11, ROS1, RET, NF1, Pik3CA for adenocarcinomas and FGFR1, FGFR2, FGFR3, TP53, STK11, EGFR for squamous cell carcinomas).
RESULTS: Reduced CHFR expression was associated with EGFR exon19/21 mutations in adenocarcinoma OR 0.23 (95%CI: 0.06-0.88) and male gender in squamous cell carcinoma (OR 0.46 (95%CI 0.23-0.92), p = 0.02).
Silencing of tumor suppressor genes (TSGs) by DNA promoter hypermethylation is an early event in carcinogenesis and a potential target for personalized cancer treatment. In head and neck cancer, little is known about the role of promoter hypermethylation in survival. Using methylation specific multiplex ligation-dependent probe amplification (MS-MLPA) we investigated the role of promoter hypermethylation of 24 well-described genes (some of which are classic TSGs), which are frequently methylated in different cancer types, in 166 HPV-negative early oral squamous cell carcinomas (OSCC), and 51 HPV-negative early oropharyngeal squamous cell carcinomas (OPSCC) in relation to clinicopathological features and survival. Early OSCC showed frequent promoter hypermethylation in RARB (31% of cases), CHFR (20%), CDH13 (13%), DAPK1 (12%), and APC (10%). More hypermethylation (≥ 2 genes) independently correlated with improved disease specific survival (hazard ratio 0.17, P = 0.014) in early OSCC and could therefore be used as prognostic biomarker. Early OPSCCs showed more hypermethylation of CDH13 (58%), TP73 (14%), and total hypermethylated genes. Hypermethylation of two or more genes has a significantly different effect on survival in OPSCC compared with OSCC, with a trend toward worse instead of better survival. This could have a biological explanation, which deserves further investigation and could possibly lead to more stratified treatment in the future.
Banno K, Yanokura M, Iida M, et al.Carcinogenic mechanisms of endometrial cancer: involvement of genetics and epigenetics.
J Obstet Gynaecol Res. 2014; 40(8):1957-67 [PubMed
] Related Publications
Endometrial cancer is increasing worldwide and the number of patients with this disease is likely to continue to grow, including younger patients. Many endometrial cancers show estrogen-dependent proliferation, but the carcinogenic mechanisms are unknown or not completely explained beyond mutations of single oncogenes and tumor suppressor genes. Possible carcinogenic mechanisms include imbalance between endometrial proliferation by unopposed estrogen and the mismatch repair (MMR) system; hypermethylation of the MMR gene hMLH1; mutation of PTEN, β-catenin and K-ras genes in type I endometrial cancer and of HER-2/neu and p53 genes in type II endometrial cancer; hypermethylation of SPRY2, RASSF1A, RSK4, CHFR and CDH1; and methylation of tumor suppressor microRNAs, including miR-124, miR-126, miR-137, miR-491, miR-129-2 and miR-152. Thus, it is likely that the carcinogenic mechanisms of endometrial cancer involve both genetic and epigenetic changes. Mutations and methylation of MMR genes induce various oncogenic changes that cause carcinogenesis, and both MMR mutation in germ cells and methylation patterns may be inherited over generations and cause familial tumorigenesis. Determination of the detailed carcinogenic mechanisms will be useful for prevention and diagnosis of endometrial cancer, risk assessment, and development of new treatment strategies targeting MMR genes.
Oropharyngeal squamous cell carcinoma (OPSCC) is associated with human papillomavirus (HPV) in a proportion of tumors. HPV-positive OPSCC is considered a distinct molecular entity with a prognostic advantage compared to HPV-negative cases. Silencing of cancer-related genes by DNA promoter hypermethylation may play an important role in the development of OPSCC. Hence, we examined promoter methylation status in 24 common tumor suppressor genes in a group of 200 OPSCCs to determine differentially methylated genes in HPV-positive versus HPV-negative primary OPSCC. Methylation status was correlated with HPV status, clinical features, and patient survival using multivariate methods. Additionally, methylation status of 16 cervical squamous cell carcinomas (SCC) was compared with HPV-positive OPSCC. Using methylation-specific probe amplification, HPV-positive OPSCC showed a significantly higher cumulative methylation index (CMI) compared to HPV-negative OPSCC (P=0.008). For the genes CDH13, DAPK1, and RARB, both HPV-positive and HPV-negative OPSCC showed promoter hypermethylation in at least 20% of the tumors. HPV status was found to be an independent predictor of promoter hypermethylation of CADM1 (P < 0.001), CHFR (P = 0.027), and TIMP3 (P < 0.001). CADM1 and CHFR showed similar methylation patterns in OPSCC and cervical SCC, but TIMP3 showed no methylation in cervical SCC in contrast to OPSCC. Methylation status of neither individual gene nor CMI was associated with survival. These results suggest that HPV-positive tumors are to a greater extent driven by promotor hypermethylation in these tumor suppressor genes. Especially CADM1 and TIMP3 are significantly more frequently hypermethylated in HPV-positive OPSCC and CHFR in HPV-negative tumors.
BACKGROUND: Total mesorectal excision (TME) remains commonplace for T1-2 rectal cancer owing to fear of undertreating a small proportion of patients with node-positive disease. Molecular stratification may predict cancer progression. It could be used to select patients for organ-preserving surgery if specific biomarkers were validated.
METHODS: Gene methylation was quantified using bisulphite pyrosequencing in 133 unirradiated rectal cancer TME specimens. KRAS mutation and microsatellite instability status were also defined. Molecular parameters were correlated with histopathological indices of disease progression. Predictive models for nodal metastasis, lymphovascular invasion (LVI) and distant metastasis were constructed using a multilevel reverse logistic regression model.
RESULTS: Methylation of the retinoic acid receptor β gene, RARB, and that of the checkpoint with forkhead and ring finger gene, CHFR, was associated with tumour stage (RARB: 51·9 per cent for T1-2 versus 33·9 per cent for T3-4, P < 0·001; CHFR: 5·5 per cent for T1-2 versus 12·6 per cent for T3-4, P = 0·005). Gene methylation associated with nodal metastasis included RARB (47·1 per cent for N- versus 31·7 per cent for N+; P = 0·008), chemokine ligand 12, CXCL12 (12·3 per cent for N- versus 8·9 per cent for N+; P = 0·021), and death-associated protein kinase 1, DAPK1 (19·3 per cent for N- versus 12·3 per cent for N+; P = 0·022). RARB methylation was also associated with LVI (45·1 per cent for LVI- versus 31·7 per cent for LVI+; P = 0·038). Predictive models for nodal metastasis and LVI achieved sensitivities of 91·1 and 85·0 per cent, and specificities of 55·3 and 45·3 per cent, respectively.
CONCLUSION: This methylation biomarker panel provides a step towards accurate discrimination of indolent and aggressive rectal cancer subtypes. This could offer an improvement over the current standard of care, whereby fit patients are offered radical surgery.
Sacristan R, Gonzalez C, Fernández-Gómez JM, et al.Molecular classification of non-muscle-invasive bladder cancer (pTa low-grade, pT1 low-grade, and pT1 high-grade subgroups) using methylation of tumor-suppressor genes.
J Mol Diagn. 2014; 16(5):564-72 [PubMed
] Related Publications
The role of epigenetics in distinguishing pathological and clinical subgroups in bladder cancer is not fully characterized. We evaluated whether methylation of tumor-suppressor genes (TSGs) would classify non-muscle-invasive (NMI) bladder cancer subgroups and predict outcome. A retrospective design included the following paraffin-embedded primary NMI tumor types (n = 251): pTa low grade (LG) (n = 79), pT1LG (n = 81), and pT1 high grade (HG) (n = 91). Methylation of 25 TSGs was measured using methylation-specific, multiplex, ligation-dependent probe amplification. The TSGs most frequently methylated in the overall series were STK11 (96.8%), MGMT2 (64.5%), RARB (63.0%), and GATA5 (63.0%). TSG methylation correlated to clinicopathological variables in each subgroup and in the overall NMI series. Methylation of RARB, CD44, PAX5A, GSTP1, IGSF4 (CADM1), PYCARD, CDH13, TP53, and GATA5 classified pTa versus pT1 tumors whereas RARB, CD44, GSTP1, IGSF4, CHFR, PYCARD, TP53, STK11, and GATA5 distinguished LG versus HG tumors. Multivariate analyses indicated that PAX5A, WT1, and BRCA1 methylation independently predicted recurrence in pTaLG, PAX6, ATM, CHFR, and RB1 in pT1LG disease; PYCARD, in pT1HG disease; and PAX5A and RB1, in the overall series. Methylation of TSGs provided a molecular classification of NMI disease according to clinicopathological factors. Furthermore, TSG methylation predicted recurrence in NMI subgroups.
Cleven AH, Derks S, Draht MX, et al.CHFR promoter methylation indicates poor prognosis in stage II microsatellite stable colorectal cancer.
Clin Cancer Res. 2014; 20(12):3261-71 [PubMed
] Related Publications
PURPOSE: Data on the prognostic significance of promoter CpG island methylation in colorectal cancer (CRC) are conflicting, possibly due to associations between methylation and other factors affecting survival such as genetic alterations and use of adjuvant therapy. Here, we examine the prognostic impact of promoter methylation in patients with CRC treated with surgery alone in the context of microsatellite instability (MSI), BRAF and KRAS mutations.
EXPERIMENTAL METHODS: One hundred and seventy-three CRCs were analyzed for promoter methylation of 19 tumor suppressor and DNA repair genes, the CpG island methylator phenotype (CIMP), MSI, the exon 15 V600E BRAF mutation and KRAS codon 12 and 13 mutations.
RESULTS: Unsupervised hierarchical clustering based on methylation status of 19 genes revealed three subgroups: cluster 1 [CL1, 57% (98/173) of CRCs], cluster 2 [CL2, 25% (43/173) of CRCs], and cluster 3 [CL3, 18% (32/173) of CRCs]. CL3 had the highest methylation index (0.25, 0.49, and 0.69, respectively, P = <0.01) and was strongly associated with CIMP (P < 0.01). Subgroup analysis for tumor stage, MSI, and BRAF status showed no statistically significant differences in survival between CL1, CL2, and CL3 nor between CIMP and non-CIMP CRCs. Analyzing genes separately revealed that CHFR promoter methylation was associated with a poor prognosis in stage II, microsatellite stability (MSS), BRAF wild-type (WT) CRCs: multivariate Cox proportional HR = 3.89 [95% confidence interval (CI), 1.58-9.60, P < 0.01; n = 66] and HR = 2.11 (95% CI, 0.95-4.69, P = 0.068, n = 136) in a second independent population-based study.
CONCLUSIONS: CHFR promoter CpG island methylation, which is associated with MSI, also occurs frequently in MSS CRCs and is a promising prognostic marker in stage II, MSS, BRAF WT CRCs.
BACKGROUND: Gastric carcinoma (GC) has one of the highest mortality rates of cancer diseases and has a high incidence rate in China. Palliative chemotherapy is the main treatment for advanced gastric cancer. It is necessary to compare the effectiveness and toxicities of different regimens. This study explores the possibility of methylation of DNA damage repair genes serving as a prognostic and chemo-sensitive marker in human gastric cancer.
METHODS: The methylation status of five DNA damage repair genes (CHFR, FANCF, MGMT, MLH1, and RASSF1A) was detected by nested methylation-specific PCR in 102 paraffin-embedded gastric cancer samples. Chi-square or Fisher's exact tests were used to evaluate the association of methylation status and clinic-pathological factors. The Kaplan-Meier method and Cox proportional hazards models were employed to analyze the association of methylation status and chemo-sensitivity.
RESULTS: The results indicate that CHFR, MLH1, RASSF1A, MGMT, and FANCF were methylated in 34.3% (35/102), 21.6% (22/102), 12.7% (13/102), 9.8% (10/102), and 0% (0/102) of samples, respectively. No association was found between methylation of CHFR, MLH1, RASSF1A, MGMT, or FANCF with gender, age, tumor size, tumor differentiation, lymph node metastasis, and TNM stage. In docetaxel-treated gastric cancer patients, resistance to docetaxel was found in CHFR unmethylated patients by Cox proportional hazards model (HR 0.243, 95% CI, 0.069-0.859, p = 0.028), and overall survival is longer in the CHFR methylated group compared with the CHFR unmethylated group (log-rank, p = 0.036). In oxaliplatin-treated gastric cancer patients, resistance to oxaliplatin was found in MLH1 methylated patients (HR 2.988, 95% CI, 1.064-8.394, p = 0.038), and overall survival was longer in the MLH1 unmethylated group compared with the MLH1 methylated group (log-rank, p = 0.046).
CONCLUSIONS: CHFR is frequently methylated in human gastric cancer, and CHFR methylation may serve as a docetaxel-sensitive marker. MLH1 methylation was related to oxaliplatin resistance in gastric cancer patients.
Yoda Y, Takeshima H, Niwa T, et al.Integrated analysis of cancer-related pathways affected by genetic and epigenetic alterations in gastric cancer.
Gastric Cancer. 2015; 18(1):65-76 [PubMed
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BACKGROUND: The profiles of genetic and epigenetic alterations in cancer-related pathways are considered to be useful for selection of patients likely to respond to specific drugs, including molecular-targeted and epigenetic drugs. In this study, we aimed to characterize such profiles in gastric cancers (GCs).
METHODS: Genetic alterations of 55 cancer-related genes were analyzed by a benchtop next-generation sequencer. DNA methylation statuses were analyzed by a bead array with 485,512 probes.
RESULTS: The WNT pathway was activated by mutations of CTNNB1 in 2 GCs and potentially by aberrant methylation of its negative regulators, such as DKK3, NKD1, and SFRP1, in 49 GCs. The AKT/mTOR pathway was activated by mutations of PIK3CA and PTPN11 in 4 GCs. The MAPK pathway was activated by mutations and gene amplifications of ERBB2, FLT3, and KRAS in 11 GCs. Cell-cycle regulation was affected by aberrant methylation of CDKN2A and CHFR in 13 GCs. Mismatch repair was affected by a mutation of MLH1 in 1 GC and by aberrant methylation of MLH1 in 2 GCs. The p53 pathway was inactivated by mutations of TP53 in 19 GCs and potentially by aberrant methylation of its downstream genes in 38 GCs. Cell adhesion was affected by mutations of CDH1 in 2 GCs.
CONCLUSIONS: Genes involved in cancer-related pathways were more frequently affected by epigenetic alterations than by genetic alterations. The profiles of genetic and epigenetic alterations are expected to be useful for selection of the patients who are likely to benefit from specific drugs.
López F, Sampedro T, Llorente JL, et al.Utility of MS-MLPA in DNA methylation profiling in primary laryngeal squamous cell carcinoma.
Oral Oncol. 2014; 50(4):291-7 [PubMed
] Related Publications
OBJECTIVES: Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) assay is a method that has rarely been exploited in DNA methylation profiling of laryngeal squamous cell carcinoma (LSCC).
MATERIAL AND METHODS: Methylation of the gene was investigated by MS-MLPA in a well-characterized series of 53 LSCC and 30 samples of healthy mucosa. Aberrant promoter hypermethylation was confirmed using bisulfite pyrosequencing, and methylation-specific.
RESULTS: Promoter hypermethylation was observed in 36 of the 53 patients (68%). CDKN2B (28%), APC (17%), RARβ (15%), DAPK1 (11%) and CHFR (11%) were most frequently hypermethylated. Aberrant methylation of CHFR was mainly a late-stage event. Methylation-specific polymerase chain reaction and bisulfite pyrosequencing confirmed aberrant methylation for CDKN2B, APC and DAPK1.
CONCLUSION: Promoter methylation profiling of LSCC using MS-MLPA identified CDKN2B, DAPK1, RARβ, APC, and CHFR as frequent epigenetic events. The clinical implications of these genes as biomarkers are highly relevant as attractive targets for cancer therapy, given the reversible nature of epigenetic gene silencing.
Novel insights in the biology of cancer have switched the paradigm of a "one-size-fits-all" cancer treatment to an individualized biology-driven treatment approach. In recent years, a diversity of biomarkers and targeted therapies has been discovered. Although these examples accentuate the promise of personalized cancer treatment, for most cancers and cancer subgroups no biomarkers and effective targeted therapy are available. The great majority of patients still receive unselected standard therapies with no use of their individual molecular characteristics. Better knowledge about the underlying tumor biology will lead the way toward personalized cancer treatment. In this review, we summarize the evidence for a promising cancer biomarker: checkpoint with forkhead and ring finger domains (CHFR). CHFR is a mitotic checkpoint and tumor suppressor gene, which is inactivated in a diverse group of solid malignancies, mostly by promoter CpG island methylation. CHFR inactivation has shown to be an indicator of poor prognosis and sensitivity to taxane-based chemotherapy. Here we summarize the current knowledge of altered CHFR expression in cancer, the impact on tumor biology and implications for personalized cancer treatment.
BACKGROUND: Although non muscle invasive bladder cancer (NMIBC) generally has a good long-term prognosis, up to 80% of patients will nevertheless experience local recurrence after the primary tumor resection. The search for markers capable of accurately identifying patients at high risk of recurrence is ongoing. We retrospectively evaluated the methylation status of a panel of 24 tumor suppressor genes (TIMP3, APC, CDKN2A, MLH1, ATM, RARB, CDKN2B, HIC1, CHFR, BRCA1, CASP8, CDKN1B, PTEN, BRCA2, CD44, RASSF1, DAPK1, FHIT, VHL, ESR1, TP73, IGSF4, GSTP1 and CDH13) in primary lesions to obtain information about their role in predicting local recurrence in NMIBC.
METHODS: Formaldehyde-fixed paraffin-embedded (FFPE) samples from 74 patients operated on for bladder cancer were analyzed by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA): 36 patients had relapsed and 38 were disease-free at the 5-year follow up. Methylation status was considered as a dichotomous variable and genes showing methylation ≥20% were defined as "positive".
RESULTS: Methylation frequencies were higher in non recurring than recurring tumors. A statistically significant difference was observed for HIC1 (P = 0.03), GSTP1 (P = 0.02) and RASSF1 (P = 0.03). The combination of the three genes showed 78% sensitivity and 66% specificity in identifying recurrent patients, with an overall accuracy of 72%.
CONCLUSIONS: Our preliminary data suggest a potential role of HIC1, GSTP1 and RASSF1 in predicting local recurrence in NMIBC. Such information could help clinicians to identify patients at high risk of recurrence who require close monitoring during follow up.
Chow JP, Man WY, Mao M, et al.PARP1 is overexpressed in nasopharyngeal carcinoma and its inhibition enhances radiotherapy.
Mol Cancer Ther. 2013; 12(11):2517-28 [PubMed
] Related Publications
Nasopharyngeal carcinoma is a rare but highly invasive cancer. As options of agents for effective combination chemoradiotherapy for advanced nasopharyngeal carcinoma are limited, novel therapeutic approaches are desperately needed. The ubiquitin ligase CHFR is known to target PARP1 for degradation and is epigenetically inactivated in nasopharyngeal carcinoma. We present evidence that PARP1 protein is indeed overexpressed in nasopharyngeal carcinoma cells in comparison with immortalized normal nasopharyngeal epithelial cells. Tissue microarray analysis also indicated that PARP1 protein is significantly elevated in primary nasopharyngeal carcinoma tissues, with strong correlation with all stages of nasopharyngeal carcinoma development. We found that the PARP inhibitor AZD2281 (olaparib) increased DNA damage, cell-cycle arrest, and apoptosis in nasopharyngeal carcinoma cells challenged with ionizing radiation or temozolomide. Isobologram analysis confirmed that the cytotoxicity triggered by AZD2281 and DNA-damaging agents was synergistic. Finally, AZD2281 also enhanced the tumor-inhibitory effects of ionizing radiation in animal xenograft models. These observations implicate that PARP1 overexpression is an early event in nasopharyngeal carcinoma development and provide a molecular basis of using PARP inhibitors to potentiate treatment of nasopharyngeal carcinoma with radio- and chemotherapy.
Pelosof L, Yerram SR, Ahuja N, et al.CHFR silencing or microsatellite instability is associated with increased antitumor activity of docetaxel or gemcitabine in colorectal cancer.
Int J Cancer. 2014; 134(3):596-605 [PubMed
] Free Access to Full Article Related Publications
Phenotypic differences among cancers with the same origin may be associated with chemotherapy response. CHFR silencing associated with DNA methylation has been suggested to be predictive of taxane sensitivity in diverse tumor types. However, the use of microsatellite instability (MSI:unstable-MSS:stable) as a predictive marker for therapeutic effect has had conflicting results. We examined these molecular alterations as predictors of chemotherapy sensitivity in colorectal cancer (CRC). Differential sensitivity to docetaxel and gemcitabine was compared to potential predictive biomarkers CHFR methylation and MSI status. Cell lines that were MSI-H/CHFR-methylated, MSS/CHFR-methylated and MSS/CHFR-unmethylated were assessed for in vivo sensitivity of CRC cell line xenografts to docetaxel and/or gemcitabine. We observed increased sensitivity in vitro to gemcitabine in cell lines with MSI and docetaxel in cell lines with CHFR inactivation via DNA methylation. In vivo treatment of human xenografts confirmed differential sensitivity, with the MSI-H/CHFR-methylated line RKO having tumor growth inhibition to each agent, and at least additive tumor growth inhibition with combination therapy. The MSS-CHFR-unmethylated line, CACO2 , was resistant to single and combination therapy, while COLO205, the MSS/CHFR-methylated line, showed tumor growth inhibition with docetaxel, but not gemcitabine, therapy. CHFR methylation in CRC cell lines predicted for sensitivity in vitro and in vivo to docetaxel, while MSI-H cell lines were more sensitive to gemcitabine. These data suggest that a subset of CRC patients would be selectively sensitive to a novel combination of gemcitabine and docetaxel, and are the basis for an ongoing clinical trial of this combination in a biomarker-selected patient population.
Gastric cancer is one of the most common malignancies and remains the second leading cause of cancer-related death worldwide. Over 70% of new cases and deaths occur in developing countries. In the early years of the molecular biology revolution, cancer research mainly focuses on genetic alterations, including gastric cancer. Epigenetic mechanisms are essential for normal development and maintenance of tissue-specific gene expression patterns in mammals. Disruption of epigenetic processes can lead to altered gene function and malignant cellular transformation. Recent advancements in the rapidly evolving field of cancer epigenetics have shown extensive reprogramming of every component of the epigenetic machinery in cancer, including DNA methylation, histone modifications, nucleosome positioning, noncoding RNAs, and microRNAs. Aberrant DNA methylation in the promoter regions of gene, which leads to inactivation of tumor suppressor and other cancer-related genes in cancer cells, is the most well-defined epigenetic hallmark in gastric cancer. The advantages of gene methylation as a target for detection and diagnosis of cancer in biopsy specimens and non-invasive body fluids such as serum and gastric washes have led to many studies of application in gastric cancer. This review focuses on the most common and important phenomenon of epigenetics, DNA methylation, in gastric cancer and illustrates the impact epigenetics has had on this field.
Koga T, Takeshita M, Ijichi K, et al.CHFR aberrant methylation involves a subset of human lung adenocarcinoma associated with poor clinical outcomes.
Hum Pathol. 2013; 44(7):1382-90 [PubMed
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Excluding epidermal growth factor receptor (EGFR) mutation, v-Ki-ras2/Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation, and echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion, the genetic alterations involved in lung adenocarcinogenesis, especially those linked to poor clinical outcomes, are still unknown. In this study, we analyzed abnormal checkpoint gene with forkhead-associated domain and ring finger (CHFR) methylation along with the above 3 mutations in 165 lung adenocarcinomas, evaluated the spectrum of each molecular abnormality, and correlated the results with clinical and pathologic variables. Reverse transcription-polymerase chain reaction assay, reverse transcription-polymerase chain reaction followed by direct DNA sequencing, and methylation-specific polymerase chain reaction were performed to detect these 3 mutations and CHFR hypermethylation. The EML4-ALK transcript or CHFR hypermethylation was found in 11 (6.7%) or 16 (10%) adenocarcinomas, respectively, whereas EGFR or KRAS mutation was detected in 48 (29%) or 13 (8%) cases, respectively. EGFR mutations occurred in patients who were negative for both CHFR hypermethylation and KRAS mutation. Among the 4 genetic or epigenetic abnormalities, only CHFR hypermethylation was significantly correlated with poor prognosis and lymphatic vessel invasion (P = .024). Histopathologically, the molecular abnormality that correlated with alveolar-destructive growth was the CHFR hypermethylation rather than the EGFR mutation (P = .03). Our results demonstrate that CHFR hypermethylation maybe one of the molecular abnormalities involved in a subset of lung adenocarcinomas with poor prognoses that might be induced by destructive growth and lymphatic vessel invasion of carcinoma cells. Thus, CHFR abnormality might be pursued as a novel therapeutic target against lung adenocarcinoma without an already-known mutation.
PURPOSE: Currently, there is no clinically validated test for the prediction of response to tubulin-targeting agents in non-small cell lung cancer (NSCLC). Here, we investigated the significance of nuclear expression of the mitotic checkpoint gene checkpoint with forkhead and ringfinger domains (CHFR) as predictor of response and overall survival with taxane-based first-line chemotherapy in advanced stage NSCLC.
METHODS: We studied a cohort of 41 patients (median age 63 years) with advanced NSCLC treated at the Atlanta VAMC between 1999 and 2010. CHFR expression by immunohistochemistry (score 0-4) was correlated with clinical outcome using chi-square test and Cox proportional models. A cutoff score of "3" was determined by receiver operator characteristics analysis for "low" CHFR expression. Results were validated in an additional 20 patients who received taxane-based chemotherapy at Emory University Hospital and the Atlanta VAMC.
RESULTS: High expression (score = 4) of CHFR is strongly associated with adverse outcomes: the risk for progressive disease after first-line chemotherapy with carboplatin-paclitaxel was 52% in patients with CHFR-high versus only 19% in those with CHFR-low tumors (P = 0.033). Median overall survival was strongly correlated with CHFR expression status (CHFR low: 9.9 months; CHFR high: 6.2 months; P = 0.002). After multivariate adjustment, reduced CHFR expression remained a powerful predictor of improved overall survival (HR = 0.24; 95% CI, 0.1-0.58%; P = 0.002). In the validation set, low CHFR expression was associated with higher likelihood of clinical benefit (P = 0.03) and improved overall survival (P = 0.038).
CONCLUSIONS: CHFR expression is a novel predictive marker of response and overall survival in NSCLC patients treated with taxane-containing chemotherapy.
Kobayashi Y, Banno K, Shimizu T, et al.Gene expression profile of a newly established choriocarcinoma cell line, iC3-1, compared to existing choriocarcinoma cell lines and normal placenta.
Placenta. 2013; 34(2):110-8 [PubMed
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Gestational choriocarcinoma is a malignant trophoblastic tumor that usually occurs in the uterus after pregnancy. The tumor is curable with advanced chemotherapy, but the molecular mechanism of choriocarcinoma tumorigenesis remains unclear. This is partly because the low incidence makes it difficult to obtain clinical samples for investigation and because an appropriate choriocarcinoma cell model to study the tumorigenesis has not been developed. We have established a new choriocarcinoma cell line, induced choriocarcinoma cell-1 (iC(3)-1), that possesses unique characteristics compared to other choriocarcinoma cell lines, including production of tumors that consist of the two types of cells commonly found in choriocarcinoma and mimicking of the clinical pathology. Existing trophoblast cell lines utilized in previous choriocarcinoma studies have had significantly dissimilar gene expression profiles. Therefore, it is important to choose an appropriate cell line for a particular study based on the characteristics of the cell line. In this study, to clarify the genetic characteristics of iC(3)-1 and to explore the tumorigenesis mechanism, we examined the gene profile of iC(3)-1 compared to those of existing cell lines and normal placental tissue. Bioinformatics analysis showed that several characteristic genes, IGF1R, CHFR, MUC3A, TAF7, PARK7, CDC123 and PSMD8, were significantly upregulated in iC(3)-1 compared to BeWo and JEG3 cells. Interestingly, HAS2, CD44 and S100P were significantly upregulated in iC(3)-1 compared to parental HTR8/SVneo cells and normal third trimester placenta. Choriocarcinoma samples also showed immunoreactivity to HAS2, CD44 and S100. In summary, the gene expression profile of iC(3)-1 suggests that studies using this cell line can make an important contribution to improved understanding of choriocarcinoma tumorigenesis.
Zhang X, Li W, Li H, et al.Genomic methylation profiling combined with gene expression microarray reveals the aberrant methylation mechanism involved in nasopharyngeal carcinoma taxol resistance.
Anticancer Drugs. 2012; 23(8):856-64 [PubMed
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Taxol is a first-line chemoagent used for treatment of nasopharyngeal carcinoma (NPC). A major obstacle to achieving successful treatment is the development of cellular taxol drug resistance. Aberrant DNA methylation has been recognized to be associated with the transcriptional inactivation of genes related to cancer drug resistance development. To identify the mechanism of DNA methylation involved in NPC taxol resistance, we applied a genome-wide DNA methylation microarray assay to reveal methylation alteration in taxol-resistant NPC cell lines (CNE-1/taxol, 5-8F/taxol, HNE-2/taxol) established previously in our laboratory. Combining with gene expression microarray, we identified drug resistance-associated genes in taxol-resistant cell lines. We also investigated the coeffect of taxol and the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) to confirm the involvement of DNA methylation. The methylation profiling revealed differential patterns between the drug-sensitive and -resistant cell lines. As a result, taxol-resistant cell lines were detected to be globally hypermethylated. Forty-eight differentially methylated genes (30 hypermethylated and 18 hypomethylated) were further identified commonly in the three taxol-resistant cell lines. Six of them (DLC1, CHFR, ABCC5, PEG10, ERBB2, and GSTP1) were independently confirmed to contribute to taxol resistance by both methylation-specific PCR and quantitative real-time PCR. Finally, we conclude that DNA methylation is closely correlated with taxol drug resistance in NPC cells. Combined analysis of DNA methylation and gene expression may enable the discovery of new therapeutic targets and prognostic biomarkers of cancers. Furthermore, DNA methylation inhibitors can reverse chemoresistance and prevent the development of acquired drug resistance.
Li X, Wang X, Yang Y, et al.RNA interference targeting CHFR enhances taxol chemosensitivity in endometrial cancer cells.
Oncol Rep. 2012; 28(1):248-54 [PubMed
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In recent years, it has been reported that CHFR may be a useful biomarker for chemotherapeutic response to microtubule inhibitors in some tumor cells. The purpose of the present study was to test the hypothesis and to elucidate the underlying mechanism in endometrial cancer cells. First, we effectively inhibited CHFR expression at both the mRNA and protein levels using siRNA targeting the CHFR gene in Ishikawa and Hec-1a cells. We found that inhibition of CHFR expression significantly enhanced the cytotoxicity of taxol to both cell types, which was confirmed again by colony formation assays. Moreover, suppression of CHFR induced a significant increase of the mitotic index and much lower numbers of cells at the G2/M phase in both cells treated with taxol, indicating mitotic checkpoint impairment. On the other hand, the number of apoptotic cells significantly increased in Ishikawa and Hec-1a cells transfected with CHFR siRNA after treatment with taxol, which was associated with cyclin B1 nuclear localization. Our data indicate that RNA interference targeting CHFR can sensitize endometrial cancer cells to taxol and CHFR may be a promising molecular target to enhance the therapeutic effect of taxol for endometrial cancer.
The mitotic checkpoint gene CHFR (checkpoint with forkhead-associated (FHA) and RING finger domains) is silenced by promoter hypermethylation or mutated in various human cancers, suggesting that CHFR is an important tumor suppressor. Recent studies have reported that CHFR functions as an E3 ubiquitin ligase, resulting in the degradation of target proteins. To better understand how CHFR suppresses cell cycle progression and tumorigenesis, we sought to identify CHFR-interacting proteins using affinity purification combined with mass spectrometry. Here we show poly(ADP-ribose) polymerase 1 (PARP-1) to be a novel CHFR-interacting protein. In CHFR-expressing cells, mitotic stress induced the autoPARylation of PARP-1, resulting in an enhanced interaction between CHFR and PARP-1 and an increase in the polyubiquitination/degradation of PARP-1. The decrease in PARP-1 protein levels promoted cell cycle arrest at prophase, supporting that the cells expressing CHFR were resistant to microtubule inhibitors. In contrast, in CHFR-silenced cells, polyubiquitination was not induced in response to mitotic stress. Thus, PARP-1 protein levels did not decrease, and cells progressed into mitosis under mitotic stress, suggesting that CHFR-silenced cancer cells were sensitized to microtubule inhibitors. Furthermore, we found that cells from Chfr knockout mice and CHFR-silenced primary gastric cancer tissues expressed higher levels of PARP-1 protein, strongly supporting our data that the interaction between CHFR and PARP-1 plays an important role in cell cycle regulation and cancer therapeutic strategies. On the basis of our studies, we demonstrate a significant advantage for use of combinational chemotherapy with PARP inhibitors for cancer cells resistant to microtubule inhibitors.
Livide G, Epistolato MC, Amenduni M, et al.Epigenetic and copy number variation analysis in retinoblastoma by MS-MLPA.
Pathol Oncol Res. 2012; 18(3):703-12 [PubMed
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Retinoblastoma is the most common primary intraocular malignancy in children. Two step inactivation of RB1 (M1-M2) represents the key event in the pathogenesis of retinoblastoma but additional genetic and epigenetic events (M3-Mn) are required for tumor development. In the present study, we employed Methylation Specific Multiplex Ligation Probe Assay to investigate methylation status and copy number changes of 25 and 39 oncosuppressor genes, respectively. This technique was applied to analyse 12 retinoblastomas (5 bilateral and 7 unilateral) and results were compared to corresponding normal retina. We identified hypermethylation in seven new genes: MSH6 (50%), CD44 (42%), PAX5 (42%), GATA5 (25%), TP53 (8%), VHL (8%) and GSTP1 (8%) and we confirmed the previously reported hypermethylation of MGMT (58%), RB1 (17%) and CDKN2 (8%). These genes belong to key pathways including DNA repair, pRB and p53 signalling, transcriptional regulation, protein degradation, cell-cell interaction, cellular adhesion and migration. In the same group of retinoblastomas, a total of 29 copy number changes (19 duplications and 10 deletions) have been identified. Interestingly, we found deletions of the following oncosuppressor genes that might contribute to drive retinoblastoma tumorigenesis: TP53, CDH13, GATA5, CHFR, TP73 and IGSF4. The present data highlight the importance of epigenetic changes in retinoblastoma and indicate seven hypermethylated oncosuppressors never associated before to retinoblastoma pathogenesis. This study also confirms the presence of copy number variations in retinoblastoma, expecially in unilateral cases (mean 3 ± 1.3) where these changes were found more frequently respect to bilateral cases (mean 1.4 ± 1.1).
BACKGROUND: DNA methylation has been widely used in classification, early diagnosis, therapy and prediction of metastasis as well as recurrence of cervical cancer. DNMT methyltransferase 1 (DNMT1), which plays a significant role in maintaining DNA methylation status and regulating the expression of tumor suppressor genes. The aim of this research was to investigate the relationship between DNMT1 and abnormal methylation of tumor suppressor genes and malignant phenotype in cervical cancer.
METHODS: Levels of DNMT1 mRNA and protein were detected using qPCR and Western blot, respectively. Cell proliferation was analyzed by MTT and apoptosis was performed by Annexin V-FITC/PI double staining flow cytometry, respectively. MeDIP-qPCR and qPCR were performed to measure demethylation status and mRNA re-expression level of 7 tumor-suppressor genes (CCNA1, CHFR, FHIT, PAX1, PTEN, SFRP4, TSLC1) in Hela and Siha cells after silencing DNMT1.
RESULTS: The average expression levels of DNMT1 mRNA and protein in Hela and Siha cells were decreased significantly compared with control group. The flow cytometry and MTT results showed that Hela and Siha cells apoptosis rates and cell viabilities were 19.4 ± 2.90%, 25.7 ± 3.92% as well as 86.7 ± 3.12%, 84.16 ± 2.67% respectively 48 h after transfection (P < 0.01). Furthermore, the promoter methylation of five tumor suppressor genes was decreased with the increased mRNA expression after silencing DNMT1, whereas there were no significant changes in PTEN and FHIT genes in Hela cells, and CHFR and FHIT genes in Siha cells.
CONCLUSIONS: Our experimental results demonstrate that methylation status of DNMT1 can influence several important tumor suppressor genes activity in cervical tumorigenesis and may have the potential to become an effective target for treatment of cervical cancer.